This relates generally to electronic devices and, more particularly, to electronic devices with displays that have thin-film transistors.
Electronic devices often include displays. For example, cellular telephones and portable computers include displays for presenting information to users.
Displays such as organic light-emitting diode displays have an array of display pixels based on light-emitting diodes. In this type of display, each display pixel includes a light-emitting diode and thin-film transistors for controlling application of a signal to the light-emitting diode.
Thin-film display driver circuitry is often included in displays. For example, gate driver circuitry and demultiplexer circuitry on a display may be formed from thin-film transistors. Often the thin-film transistors are required to be all N-type or all P-type transistors. However, it can be challenging to pass logic one values with N-type transistors and logic zero values with P-type transistors. To help pass logical values at power supply voltages, bootstrapping capacitors may be used to store charge, which is used to boost transistor gate voltages above or below power supply voltages. However, if care is not taken, transistor leakage currents can potentially drain the charge stored in the bootstrapping capacitors. It would therefore be desirable to be able to provide improved electronic device displays.